Hacker Hannah Sweet, known as “Cosmo” and @CosmoTheGod on Twitter, said UGNazi took Twitter down for 40 minutes worldwide with a “distributed denial of service” attack and the hackers are continuing to do so.

Sweet said that the group attacked Twitter because of the site’s support of Cyber Intelligence Sharing and Protection Act (CISPA), a bill that allows the federal government and private businesses to share information about possible cyber threats.

And they’ve posted a target list of other places they plan to take down, including Google (among others).

This wasn’t due to a hack or our new office or Euro 2012 or GIF avatars, as some have speculated today. A “cascading bug” is a bug with an effect that isn’t confined to a particular software element, but rather its effect “cascades” into other elements as well. One of the characteristics of such a bug is that it can have a significant impact on all users, worldwide, which was the case today. As soon as we discovered it, we took corrective actions, which included rolling back to a previous stable version of Twitter.